Abqn hamburger



A. HAMBURGER.

CDLUR PHDTUGRAPHY.

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Patnted July 1, 1919.

| l l l l I l l l I l l I l l i l l Hjamurger. i fm? .faQ/ML Mmmm ARQN HAMBURGER, F MAYFAIR, LONDON, ENGLAND.

COLOR PHOTOGRAPHY.

Specification of Letters Patent.

ratented July 1, 191e.

Application' mee January ao, 1919. serial NQ. 272,201.

' is a specification.

This invention relates to the preparation of photographic reproductions of objects in natural colors, and to apparatus therefor.

The invention embraces a multi-color process in which complementary color negatives say a red or orange red value negative and a blue or blue green value negative, one of which is reversed, are accurately superimposed, on opposite sides of a doubly sensitized film and photochemically printed. The combined positive is then bleached and dyed or pigmented in' separate or simultaneous operations each side its res ective color, and may itself be used' as a nished two-color photograph or it maybe combined after clearing with a yellow value positive prepared preferably 'by the process of my British Patent No. 20,880, September 21, 1911, according to which mercury-silver iodid gives the yellow color.

The invention also embraces a method of andv means for dyeing the two sides of the positive wlthout risk of staining either side y the reagents used on the other.

The invention further provides a dyeing I frame adapted for simultaneous dyeing of both sides of the positive'.

In carrying this invention into effect in one form, I prepare a red value negative and a blue value negative of the colored object to be reproduced by photographing through color screens by means of a camera in the usual way. If these negativesare prepared with an ordinary camera, then I reverse one of the negatives. I prefer, however, to employ a camera .embodying the invention de-V atent to Conrady andl scribed lin British Hamburger No. 28, 22, December ,13, 1912, (corresponding to S. patent to Conrady et al., 1,140,576, May 25, 1915), i. e., a type of camera with which both negatives can be roduced at the same time, one of them belng reversed. These negatives represent the red value of the object and the blue value of the object respectively and should be practically complementary: I superimpose these .negatives accurately in relation to one another upon opposite sides of a doubly sensitized film, z'. e., a film having emulsion on both sides. I then print through each of these negatives by suitable simultaneous illumination from opposite sides and develop and fix as usual. l/Vhen the negatives are truly complementary and of practically the same density I find that no protective screening is required if equal illuminations be used and that the color'values print without interference with one another. I then bleach the double positive, say by the welll-known Traube method. The object of this process is to convert the silver image into a silver salt which has a high affinity for coal tar colors.

In order to obtain an image more stable and resistant to washing, &c., I prefer to employ a bleaching solution made up as follows 2 fluid ozs. of `a solution of l oz. of vpotassium iodid in 9 ozs. of water are added slowly and with stirring to 4 fluid ozs. of a solution of 41 oz. of otassium bichromate and 9 ozs. of water. o the resulting solution is added very slowly and with stirring 16 fluid ozs. of water containing 80 minims hydrochloric acid. The developed and fixed` film which is to be colored is soaked in cold".

water and allowed to drain. It is then introduced into the bleaching bath, until the silver in the image is completely bleached. It is then thoroughly washed `in cold water, and then in warm water up to 140 F., until all reddish and yellowish stains disappear, and the non-silver spaces are thoroughly colorless and clear. The positive is then ready for dyeing. The positive thus pro- Aduced is then placed in a dyeing frame as shown in the accompanying drawings:

Referring to the accompanying v drawingsz- Figure 1 is a side elevation of a dyeing frame constructed according to my invention.

Fig. 2 is a sectional elevation on line scaled with a water-tight joint. The second half of the frame is also provided with a ring of j ointing material b', and is placed on the top of the film, clamping the latter against the other half frame all around its edges in a water-tight manner. The outer side of' each of' the halves of the frame is provided with a sheet of glass d d sealing against the edges of the frames and thus forming a tank chamber on each side of the film. The two halves ofthe frame may be arranged for rapid opening. and closing by means ot' hinges e along the bottom edge and wing nuts and screws f on the top edge. The tank chambers on each side of the film are provided with outlet passages g at their lower ends, and these are controlled by suitable cocks or valves z.. Inlets i i are provided at the top edges of the tank chambers, for the admission vof" the dyeing fluids. Means are also provided for the outlet of air by the valves 7c as the fluid is introduced.

adapted to be closed at will. To prevent sagging of the film, the two fluids may be introduced simultaneously.

The film introduced into the dyeing tank s just described, and clamped therein, is dyed l' silver parts are cleared of' dye. .35

l A bythe introduction of the appropriate dye- 30 ing fluids on each side.' The film may thus be simultaneously dyed on both sides. The dyeing fluids are then run ofl and the positive thoroughly washed, until all the non- Fixing is then effected in a solution of sodium thiosulfate (hypo) -containing 5 percent. of

tannic acid, and the filmv is then washed and dried in the ordinary way.

The positive film thus obtained is then combined by superposition with a yellow tone positive representing the yellow color" Vvalue of the ob]ect photographed. Where a two-color result only is desired, a posi.-4A tivel similarly made from orange red and blue green value negatives and dyed relatively blue green and orange red, may be mounted on paper or used as a transparency. The yellow positive is preferably obtained I by the use of mercury-silver iodid, as theV y soaking them for five minutes in a bleaching and pigmenting solution as described below,

and thus the silver images are converted into dyed or pigmented images. The .papers the following ingredients The air eXit valves c 7c may bel or the like thus soaked are pressed into contact with the two sides of the film on which the required positive complementary color images have been printed. They are thus allowed to remain in contact a suitable time say 20 to 25 minutes. paper is developed in hot water as usual or the dye paper washed only in c'old water. Simultaneous bleaching and pigmenting or dyeing is thus effected.

' The required solution is. prepared from Copper sulfate f 4 ozs. Potassium bromid; 4 1400 grs. Potassium bichromate 180 grs. HC1 8O minims.

The copper sulfate is dissolved with the potassium bromid in 20 ozs. of water and the potassium bichromate in another equal quantity of water to which the HC1 is also added. The two solutions are then mixed slowly while stirring well and the resultiiig solution is ready for use.' The dyes required are for greenish blue basic 4methylene blue which should be nearly as possible minus Then the carbonY red and for magenta red basic fuchsin. red

which should be as nearly as possible minus green. .n

The apparatus herewith described is not claimed in the present application, but forms 'the subject matter vof a divisional application Serial No. 298,527, filed by me May 20, 1919.

,Having now described my invention what I claim as new and ,desireto secure by Letters Patent is 1. A multi-color process comprisin ac'- .curately registering and photo-chemically printing complementary color-value lnegatives, oneof which iS reversed, respectively upon both sides of a positive film sensitized Y on both sides, andthereafter while maintaining the said positive in a vertical position Y between two dissimilar liquids in contact therewith, but not in contact with each other, practically simultaneously developing 'the respective colors on the two sides of the'combined positive so produced.

2. A multi-color process comprising accurately registering and photo-chemically printing. complementary color-value negatives, one of which --is reversed, respectively upon both sides of a positive film sensitized Y on both sides, and thereafter while maintaining the said positive in a position between two dissimilar liquids in contact',A

therewith, but'not in'contact with each other,

practically simultaneously developing .the

respective colors in the two sides of the combined positive so produced, and' combining therewith a vyellow value positive.

.3. A multi-color process comprising accurately registering and photo-chemically lprinting complementary color-value negatives, one having a red to orange-red value its respective color, the combined positive and the other having a blue to bluebeing so framed as to form tanks for dyeing, green value, one of which negatives is reone Wall of each being formed 'by the film 10 versed, respectively upon'opposite sides of itself. 5 a positive film lsensitized on both sides and I In testimony whereof I have signed my ractically simultaneously coloring the comname to this specication. ined posltive so produced on each side with ARON HAMBURGER. 

